I reckon it's highly dependent on quality of content and type of audience you gathered on your page. Facebook is presenting your post to users and their friends

I reckon it's highly dependent on quality of content and type of audience you gathered on your page. Facebook is presenting your post to users and their friends but it doesn't mean that they have to click like. The conclusion would be to only sponsor posts that few people will like I would go in a completely opposite direction in here - sponsor the posts that you know will go viral. It will have a bigger impact and might bring more people to your page.